U.S. Pat. No. 5,965,963 describes a linear motor made up of a secondary component and a primary component (stationary component), the secondary component implementing the triggering of the coils integrated in the path with the aid of position-sensing sensors such as Hall-effect sensors (FIG. 1B, FIG. 3), which are mounted along the path, and with the aid of a magnet situated on a secondary component. This may have the disadvantage that the mechanical system for sensing the position becomes increasingly more and more complex as the number of secondary components is increasing, reaching its limit with four to six secondary components (FIG. 10). Moreover, it is more difficult to expand an existing path since the implementation of rail and secondary component depends on the number of secondary components. Also, the already existing control has been configured for the specific application case, and a modification of the system configuration requires considerable time and technical effort. The concept of using position sensing may also have the disadvantage that the generated signal will be falsified if even a single sensor breaks down, so that an eventual collision or a malfunction is thus virtually preprogrammed. In addition, the wiring required for analyzing all sensor signals is considerable. This may drastically increase the susceptibility to faults, in particular under adverse circumstances.
U.S. Pat. No. 5,023,495 describes a d.c. linear motor, which theoretically has an infinite number of secondary components that can be controlled independently. Here, the position is sensed with the aid of, for instance, permanent magnets affixed on the secondary component whose magnetic field is sensed by sensors (FIG. 7, reference numerals 8, 46) mounted on the primary component. No further description of the control of the secondary components is provided. The description essentially encompasses the mechanical configuration of primary and secondary component as well as their cooperation. It may be disadvantageous that an external control would have to assume the entire process coordination and only straight movement paths can be realized.
U.S. Patent Application Publication No. 2002/0180279 describes a modular system made up of linear motors. FIGS. 17 through 21 illustrate the flexibility of the system based on the realization possibility of movement paths that, theoretically, have any configuration. In one illustrated potential realization form, the secondary component includes a battery-powered signal-processing device (FIG. 5), which carries out the position sensing by remote control via radio and reports it to a central control unit. However, the configuration of the secondary and primary components is similar to the design disclosed in U.S. Pat. No. 5,965,963 and hence may have the same disadvantages. Here, the movement is controlled by a central motor controller, which communicates with module controllers via a network and therefore controls and administers all secondary components. With the aid of the received position data, the controller network must calculate all information relevant for the movement control such as acceleration, speed, shear force, and trigger the coils accordingly. The control of the secondary components becomes more complex with each increase in the number of secondary components since the position must be detected for every secondary component, and the corresponding coils on the path formed by the primary components must be switched such that all secondary components move completely independently of each other and collisions are prevented. In addition, to avoid losses, only the coils that are directly underneath the secondary component should be triggered.
U.S. Pat. No. 6,502,517 and European Published Patent Application No. 0 580 107, which both relate to magnetic levitation systems, also should be mentioned in this context. U.S. Pat. No. 6,502,517 discusses the mechanical and electrical aspects of such a system realized with the aid of a linear motor and proposes a design approach for the non-contacting transmission of electrical energy for electrical components on the floatingly supported secondary component. The contents of European Published Patent Application 0 580 107 describes a levitation system, the focus being on, among others, the control of the air gap as a function of the loading of the suspended component. For this purpose, the moved component includes a control unit, which permanently monitors the air gap and initiates appropriate countermeasures as soon as the required setpoint changes. The essence of the distance control are electric magnets, which are mounted on the moved component and via whose current supply the path distance is able to be adjusted.